1. Field of the Invention
The present invention relates to regenerative control technology in an electric power-assisted vehicle.
2. Description of Related Art
There are electric power-assisted vehicles, such as electric bicycles assisted by battery power, which use sensors provided on brake levers. The sensors respond to the usage of the brakes by the rider in order to enable regenerative operation of the motor. This stores the kinetic energy of the vehicle into the battery, and improves the travel distance of the vehicle.
There is technology that controls the duty in PWM (Pulse Width Modulation) control so that electric regenerative braking force, generated by the regenerative charging when only one of either of the brakes is used, is smaller than the electric regenerative braking force generated by the regenerative charging when both of the brakes are used together. This way, with a simple configuration and a low cost, the shock is reduced during the start of regenerative charging when only one of either of the brakes is used, and when both brakes are used together, the regeneration value is increased as compared to when only one of either of the brakes is used, which results in a large regenerative braking force generated due to the regenerative charging.
However, there are times when the rider does not necessarily progress from using one brake to using both brakes. Sometimes the rider starts by using both brakes. In such a case, the conventional technology described above generates a sudden and large regenerative braking force, and the rider may feel a shock due to that regenerative braking force. In addition, the relationship between regenerative braking force and rider comfort has not been given careful consideration in the conventional technology described above.